Furnace-roof construction



July 8, 1924. 1.5o0,240

R. E. GRIFFITH FURNACE ROOF CONSTRUCTION Filed 10v, 5, 1922 V I5Sheets-Sheet 1 FIG: I-

INVENTOR:

A TTORNEYS.

July 8, 1924. 1500,240

R. E; GRIFFITH FURNACE ROOFICONSTIRUCTI'ON Filed NOV. 5, 1922 3Sheets-Sheet 2 FIQ I 36 z a 51 25 i6 d4" /-;Z2 12 v J4:

WITNESSES: IN VEN TOR:

gaymondfi. h %TORNEYIS.--

July 8 i924.

R. E. GRIFFITH FURNACE ROOF CONSTRUCTION INVENTOR:

BY M I TTORNEYS.

Filed Nov. 55, 1922 3 Sheets-Sheet 3 216: H

WITNESSES:

: urpose 10f illustrating Patented July 8, 1924.

UNITED: STATES 1,500,240 PATENT OFFICE.

ImmoNnn GRIFFITH, or PHILADELPHIA, PENNSYLVANIA.

FURNACE-ROOF CONSTRUCTION.

I Application filed November 3, 1922. Serial No. 598,754."

To all whom it may concern:

temperature furnaces, such as basic open hearth and electric steelfurnaces, reverberatory copper smelting and other types of furnaceswhere chemical action is destructive to the refractory roofs andlinings.

An object of the invention is to permit the construction of furnaceroofs of refractory brick of a chemical constitution having capacity toresist the corrosive action of slag and furnace gases but which haveheretofore been discarded for such usein favor of brick of greaterphysical strength but which are not resistant to corrosive.

action.

The invention contemplates the provision of structural details for thepurpose of accomplishing the above stated objects, which consists inbonding elements vinserted between the bricks in the course of roofconstructionto permit expansion and contraction of the roof withoutdisintegration when heating and cooling, and a novel suspension meanswhereby the roof structure is support ed from above at selected orsalient points against internal strains due to its own weight and sothat the roof may remain intact even when fractured or partlydisintegrated. Y

. Another object of the invention is to provide refractory brick for theroof construction of metallurgical furnaces in which the bonding facesare so formed as to permit interlocking of the brick and hence themutual support thereof so as to ensure'a solid structure capable in ahigh degree of resist- 7 ing disintegration.

The inventive concept involved in the performance of the certain objectsoutlined above is capable of receiving av variety of mechanicalexpressions, one of which for the the invention is shown in theaccompanying drawings, but it is to be expressly understood that suchdrawings are for the purpose of illustration only and are not designedto define the limits of the invention, reference being had to theappended claims for this purpose.

In addition to the foregoing this invention comprehends improvements inthe details of construction and arrangement of the correlated parts tobe'hereinafter described and illustrated by reference to theaccompanying drawings, in which Figure I is a view in longitudinalsection of an 0 en hearth furnace of conventional type having a roofstructure embodying my improvements. I i Figure 11 is a view of thefurnace in transverse section.

Figure III is a detail view in section of a combined expansion plate andsuspension member forming part of the present inven- 1 tion andillustrating its cooperative relation to the brick'of a roof structure.

Figure IV is a view in perspective of on of the expansion plate hangers.

Figure V is a view in elevation of a hanger yoke forming part of asuspension unit.

Figure VI tion of an expansion plate hanger, and a, portion of asupporting member.

Figure VII is a view in perspective of an arch block used in roofconstruction; and

is a view in longitudinal sec-- re VIII is a view in perspective of askew back block forming part of the endconstruction of a roof span.

In the usual type of roof. construction for furnaces wedge-shapedrefractory brick are employed to form an arched roof spani supportedsolely by virtue of inherent stability residing in arched construction,the end ning the entire width of the furnace and thrust of the roofbeing taken up and con-' fined within heavy metallic columns stayedtogether so that any expansion of the roof oc-- curring must necessarilyresult in upward bowing of the roof, since the confining structurementioned'prohibits any lateral expansion of the roof. Owing to thetremendous strains to which the roof is subjected dur-.

ing expansion, a typeof building unit or brick is employed which willresist the compression strains and for thisreason silica brickis usuallyused. This material is .how-

ever open to the objection that because of the acid constitution'of suchbrick they are easily corroded and disintegrated the re- 7 action ofmolten basic slag or the pone-I trating corrosive laden gases of thebasic open hearth and other melting and smelting furnaces. The presentinvention contemplates the utilization of refractories which are moreresistant to chemical action among which may be mentioned magnesite andchromebrick, which however have failed of extensive adoption by reasonof their physical weakness and incapacity to efliciently withstandcompressional strain.

The principles of construction employed in the use of this type ofrefractory material include the support by suspension of the roofstructure so as to relieve internal compression due to end thrust at thesides of the roof, and the bonding of the brick so as to permitexpansion or contraction ofthe bond itself without subjecting the brickto the strain of heat expansion.

The exact means whereby the above stated principles are carried out maybe varied and hence I have therefore shown one illustration only whichwill be suflicient to indicate to others skilled in the art the mannerof employment of the apparatus and to suggest any alterations that maybe necessary to meet the requirements of specific instances of usage.

Proceeding to a description of the draw-' ings 10 indicates the hearthof a conventional form or reverberatory open hearth steel furnaceincluding the end walls 11,

' the side walls 12 and the roof structure indicated comprehensively at13. The sides of the furnace structure are supported by the provision ofopposed pairs of longitudinally spaced buck stays 14 tied together bymeans of the rods 15 in the usual manner.

The roof structure, in accordance with the usual method is formed ofrefractory arch blocks 16 of wedge formation assembled to form an archedor upwardly bowed roof which is supported along its edges upon skew backblocks 17 rested upon the walls 12 and abutting against longitudinalchannel beams 18 which are enclosed by the buck stay's 14:. The brick 16may be of the usual type of basic refractory material having smoothsides, but for the purpose of my invention are preferably corrugatedalong their bonding faces by the formation therein of transverse ridgesand grooves 19 so as to cause interlocking of the brick when assembled.In-a similar manner the bonding faces of the skew back blocks 17 arecorrugated as at 20 for interlocking engagement with the adjacent blocksof the span. By reason of the interlocking engagement of the brick thestructure is rendered-self sustaining and more resistant todisintegration, since upon fracture thereof the fragments will tend toremain in place.

In conjunction with this type of roof con struction I employ what I termexpansion bonding plates which are also utilized as hanger membersforming part of a suspension rigging to be described. The suspensionplates and the manner of'their use are shown in Figures III, IV and VIfrom which it will be noted that they consist of a strip of metal, ofany kind found suitable for the purpose and bent transvesely to formspaced plates 21 and 22. The point of flexure of the strip is rounded tocylindrical formation as shown at 23 to permit a pin or rod 2 1 to beinserted therein, said portion 23 being cut away to form an opening 25for a purpose to be presently noted. The plates 21 and 22 are corrugatedto provide transverse ridges and grooves 26 for interlocking andintimate bonding engagement with the grooved faces 19 of the refractoryelements. One of the plates, shown in the drawing at 22 is punched atfrequent intervals to form uncompleted openings 27 the remainingportions of the metal being bent inward to form yielding spacing lips28; and the end of one of the plates, namely 22 in the instance given isbent laterally to form a rib 29 which contacts with the adjacent end ofthe other plate to retain said plates in spaced relation and to form afusible seal.

During the construction of the roof one of the bonding elements isinterposed between adjacent bricks 16 at points which-are 4 deemedsalient in resisting gravity to effect a substantial support forthereof, in transversely spaced relation as seen in Figure II, and inlongitudinal spaced relation as shown in Figure'I. It will be noted fromFigure I that the hangers in any longitudinal course are arranged in endto end engagement and at varying levels toconform to the shape of theroof.

The suspension rigging consists of a plurality of lateral supportingbeams 30 arranged in longitudinal spaced relation to a number.sufiicient to ensure ample support for the structure and preferablycurved to follow the contour of the roof span. The ends of said beams 30abut against and are supported by longitudinal beams 31 secured to theinner faces'of the buck stays 14 at the proper elevation.

Supported upon the transverse beams 30 are a plurality of hanger yokesshown in detail in Figure V and comprising a plate 32 formed withdepending spaced flanges 33 to engage opposite sides of the'beam 30,which may be either of unit construction or composed of two channelirons as shown. The flanges 33 are strengthened by the provision of ribs3 1 integrally connecting said flanges and the bar 32, the latter beingapertured at spaced points to receive the threaded ends of vertical eyebolts 35 having their looped ends depending toenter lt-he openings 25 ofthe bonding elements and to IOU receive the hinge pins or rods 24. meansof this arrangement the ex ansion plates are supported in groups of tree, although the number maybe varied or thejmanner of groupmg maybeotherwise Varied to conform to the requlrements of specificcircumstzxices.

wing nut 36 is applied to the protrudmg threaded end of. each' eye boltand Washers 37 are interposed between the wing Figure VI. After the roofstructure is com-- pleted and the parts assembled, and durin the gradualheating of the furnace the r00 expansion is taken up'by yielding of thespacing hps 28 which permit the blocks to expand and the plates 21 and22 toamove together without inducing any compresslonal strains in theblocks themselves. Before. the maximum operating temperature of thefurnace is reached the lip 29 ofea'ch hanger will fuse and the metalwill unite with the surface of the adjacent blocks to form a seal at theside of the roof exposed to the heat of the furnace, and the roofstructure will thus be thoroughly sealed and rendered impervious to the,escape of gasesand supported efficiently without permitting internalstrains which may tend to fracture the refractory material. If, howeverthe oints between the bricks at one or more points should not have beenproperly sealed 'by fusion of the metal, nor the roof suflicientlyexpanded to close the joints an effective sealing and compactness ,ofthe structure may be procured by loosening the wing nuts 36, to anamount required in' order to permit the roof to move downward slightlyor to settle far enough to close the joints, without entirely relievingthe supporting rigging of the weight of the roof, so that the riggingmay still sustain a sufficient proportion of th total weight of the roofand thereby avoid crushing of the brick. By adjusting all of thewingnut's a general raising or lowering of the roof may be accomplished,or a local change in elevation of any portion of the roof may beeffected by judiciously adjusting the nuts of the hangers supportingthat portion of the roof to be affected. Because of the cor- I,

rugated surfaces of the hanger plates an efiicicnt bond is ensuredbetweenthe blocks and hanger plates tending to prevent the roof materialfrom falling-away from the hanger plates. By appropriate adjustment ofthe wing nuts 36 wherever deemed necessary the weight of the roof may beequally distributed throughout the supporting-rigging and excessivestrains at any po1nt 1n the roof may be taken up in this manner.

From the foregoing it will be seen that relatively soft or friable brickmay be used in furnace roof construction as the expansion plates orbonding elements will effectively act to relieve the brick of all strainduring heat expansion of the structu e. In fact the brick is relieved ofall strain even that incidental to the weight of the structure, sincethe rigging will support the weight of the roof thus relieving the roofof end thrust at the ends of the span which isv present in ordinary archconstruction having only end supports for the roof.

During the operation of furnaces it frequently develops that cracksoriginate and I the release spread along 'the roof causing of largepieces which fall into the furnace resulting in serious losses anddelay. Itwill be seen that with my improved construction thisdisadvantage will belargely eliminated.

as any portion that may crack away from the main portion of the roofwill be held in place between the expansion hangers or between thehanger and an adjacent bIlCk, the corrugations between the brick orbetween the. brick andhangers effecting suflicient mechanical bond.

Other advantages will readily occur tov those familiar with the art toinvention appertains.

Having thus described my mvention, I claim:

1. In a metallurgical furnace, a'roof structure composed of refractoryelements, noncombustible inserts between the refractory elements topermit expansion of the strucwhich this ture by heat with the impositionof minimum strain within'the elements, and means supporting the roofstructure against lnternal strains incidental to its own weight.

2. In a metallurgical furnace, a'roof structure composed of refractoryelements, noncombustible yielding means inserted between the elementstopermit expans1on of the structure by heat with the lmposltion ofminimum strain within the elements, and

means supporting the roof structure against internal strains incidentalto its own weight;

' 3. In a metallurgical furnace, a roof struc- 1. I

ture composed of refractory elements, means effecting bonding engagementwith the adjacent faces of said elements, and yielding means interposedbetween said last men-. tioned means. to permit expansion of the}structure by heat. with the ImPOSltIOII: of minimum strain within theelements, and

means supporting the structure against internal strains incidental toits own weight 4. In a metallurgical furnace, a roof struc ture composedof refractory elements, 31-00??? .of ad acent elements comprising platesadapted for intimate bonding connection to said elements, yieldablespacing elemenfis.

formed with one plate and engagin other to retain said plates in spacedre ation and thereby permit expansion of the structure by heat with theimposition of minimum strain within the elements, and means supportingthe structure against internal strains incidental to its own weight.

6. In a metallurgical furnace, a roof structure composed of refractoryelements, a

bonding element inserted between the faces of adjacent elements,comprising a strip of material bent to form spaced plates, said.

plates being corrugated to effect intimate 1 thereby onding connectionto said elements, one of said plates being formed with integralyieldable lips engaging the other plate to retain said plates in spacedrelation and thereby permit expansionof the structure by heat with theimposition of minimum strain within the elements, and means supportingthe structure against internal strains incidental to its own weight.' g

7. In a metallur ical furnace, a roof structure com osed o refractoryelements, a bonding e ement inserted between the faces of adjacentelements comprising a strip of metal bent upon itself to form spacedplates, said lates being corrugated to effect intimate onding connectionto the elements and one of said lates being punctured to provide inwardy extending yieldable lips retaining the plates in spaced relation, topermit expansion of the structure by heat, wit the imposition of minimumstrain within the elements, pins inserted in'the bights of said bondingelements, and a suspension rigging located above the roof and engagingsaid ins to support the structure against mtern'a strains incidental toits own weight.

8. In a metallurgical furnace, a roof structurecomposed of refractoryelements, and non-combustible yieldable bonding elements interposedbetween the refractory elements to permit expansion of the structurebyheat with the imposition ofminimum internal strains.

9. In a metallurgical furnace, a roof-structure composed of refractoryelements, and bonding elements inserted between said refractoryelements, composed of plates adapt ed for effective bonding connectionto said refractory elements, and yiledable spacing means between theplates to give way under ex ansion of the structure by heat and to reuce internal strains to a minimum resulting from such expansion.

- 10. In a metallurgical furnace, a roof structure composed of friablerefractory elements having their bonding faces wholly and transverselycorrugated, and a suspension means engaging the roof structure atsalient points along the span to support the structure against internalstrains incidental to its own weight. g

11. In a metallurgical furnace, a roof structure composed of friablerefractory elements having their bonding, faces wholly and transverselycorrugated, and a suspension rigging mounted above the structure andhaving connections to said roof structure at points across the span andlongitudinally of the structure to en port the same against in' ternalstrains inci ental to its own weight.

12. In a metallurgical furnace, including the side walls and buck stays,a roof structure of friable refractory elements having the bonded faceswholly and transversely corrugated, and a riggingcomprising lateralbeams supported u on the buck stays in longitudinal space relation, andhanger elements arranged at salient points along the span to resistgravity and having effective hinged engagement with the roof structureto support the. latter strains incidental to its wei t.

13. In a metallurgical furnace, including Slde walls and vertical buckstays, a roof structure composed of friable refractory elements havingthe bonding faces wholly and transversely corrugated, a suspensionrigging supported by the buck stays, and transversely corrugated hangermembers forming part of said suspension rigging engaging the roofstructure and adapted to ralse or lower said roof structure to effectstructural compactness.

14. In a metallurgical"furnace, a roof structure composed of friablerefractory elements having the bonding faces wholly and transverselycorrugated, a rigging above the structure to support the same includingtransversely corrugated hanger elements engaging the roof structure atsalient points to resist gravity, and means for permitting verticaladjustment of said hanger elements independently to effect local raisingor lowering of the structure to ensure compactness.

15. ,In a metallurgical furnace, including side walls and buck stays,lateral beams supported upon the buck stays, and transversely corrugatedhanger elements carried by said beams including depending rods havinghinged engagement with the roof structure at salient points to resistgravity, and. adjustable elements for threaded conagainst internal gnection to said rods adapted to effect local or general raising orlowering of the roof structure.

16. In a metallurgical furnace, a roof structure composed of refractoryelements in bonded relation having the bonding faces wholly corrugatedfor interlocking engagement to render said roof structure selfsustaining.

17. In a metallurgical furnace, a roof structure composed of refractoryelements in bonded relation having their meeting faces wholly andtransversely corrugated to effect interlocking of the elements.

18. A hanger for the roof suspension of metallurgical furnaces,comprising a trans-.

versely corrugated and flexible bonding element adapted to beincorporated in the roof structure, and a supporting element hingedlyconnected to said bonding element having capacity. to efiect verticaladjustment of said element when the parts are assembled and supported.

19. A hanger for the roof suspension of metallurgical furnaces,comprising a'bonding element in the form of connected spaced plateshaving yieldable spacing means and adapted to be incorporated in theroof structure, and a supporting rod having a threaded adjustableelement for cooperation with any suitable support to effect verticaladjustment of said bonding element.

20. A hanger for the roof suspension of metallurgical furnaces,comprising a bonding element adapted to be incorporated in the roofstructure and comprising a U-shaped metallic plate having yieldablespacing elements therebetween, a pin inserted in the bight of the plate,an eye bolt having its loop receiving said pin and its opposite endthreaded, and a nut applied to said end.

21. A bonding element for interposition between the refractory brick ofa roof structure for furnaces, comprising spaced members adapted forintimate bonding engagement with the adjacent faces of the brick andyieldable means retaining said members in spaced relation.

22. A bonding element for interposition between adjacent brick of afurnace roof structure, comprising a plate bent to U-formation andcorrugated to effect intimate bonding engagement with the brick, one ofsaid plates being punctured to provide yieldable lips engaging the otherplate to retain said plates in spaced relation.

23. A bonding element for interposition between brick of a furnace roofstructure, comprising plates, means retaining the plates in spacedrelation, and a fusible lip closing the space between the plates andadapted to fuse and close the space when heated.

24. A building block for the roof construction of metallurgical furnaceshaving its bonding faces wholly and transversely corrugated to provideinterlocking engagement of the blocks.

In testimony whereof, I have hereunto signed my name at Philadelphia,Pennsylvania, this 31st day of October 1922.

RAYMOND E. GRIFFITH.

Witnesses:

JAMES H. BELL, E. L. FULLERTON.

